Dave Bailey
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| posted on 11/3/12 at 12:32 PM |
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lambda Sensor Position
Hi!,
I am running a DTA S60 on an ST170 engine with a 4 - 1 exhaust... I have not been able to get the engine to run right since having it tuned.. I
have two Lambda bosses in the pipe leading to the CAT one about 12" from the cat and the other very much nearer the 4-1 collector. The tuner
used the boss near the CAT to set the car up and didn't have closed loop control enabled on the ECU whilst doing it because he used his own
sensor.. It seemed to MAP ok but hasn't really run well off load... Load the engine up and accelerate quickly and it goes very well.. Anyway
emissions were all over the place when I put the car on a gas analyser with HC being 850+ and a high O2... 8% plus... The car seems to have a slight
miss fire but again only seems to be there off load. I have enabled the close loop control on the ECU but not really much different... I have replaced
the header to downpipe gasket incase this was causing an air leak but no joy... I was wondering if it was possible to have the Lambda sensor too close
to the collector?
Fuel pressure seems steady @ 3 bar
Any other ideas would be much appreciated...
thanks
Dave B
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matt_gsxr
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| posted on 11/3/12 at 02:47 PM |
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High O2 and high HC is a difficult combination to get to.
Normally too much fuel is high HC but not high O2.
Conversely too little fuel will give you high O2 but no HC.
So, my guess is you have a slight sparking problem, or one of your injectors is blocked or leaking.
Do all the headers warm up at a similar rate when you start the engine from cold?
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MikeRJ
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| posted on 11/3/12 at 03:48 PM |
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quote:
Originally posted by matt_gsxr
High O2 and high HC is a difficult combination to get to.
Classic symptoms of a weak mixture misfire. Since you get the fuel/air mixture shoved out of the exhaust port without getting burnt you get high
oxygen and high HC.
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Dave Bailey
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| posted on 11/3/12 at 05:02 PM |
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I looked at the plugs and they are quite black and sooty around the electrode but brown on the very tip....
Dave B
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T66
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| posted on 11/3/12 at 05:05 PM |
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Is it not the case with closed loop running, the ecu needs some time running to adjust itself based on the lambda outputs ?
Hence running dog like ?
If you have paid for a rolling road setup, surely it needs to go back, as its not right.
From the Closed loop section of the S60 manual, this bit caught my eye.
The most likely source of problems when using this feature is that the mixture adjustment varies wildly with major positive and negative
adjustments of the fuelling adjustment. This is caused by either the lambda sensor being too slow for the required loop frequency of the other
settings for the lambda sensor being incorrect. Stop the engine immediately and adjust the settings in Lambda Settings.
[Edited on 11/3/12 by T66]
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